I noticed that my back wheel has had a bit of play in it recently, and I thought it would make a good post! First off: What was going wrong? Well, the rear hub is made up of the axle, the axle hardware, the bearings and the hub. Graphic time!
The hub rests on the bearings, and the bearings rest on the cones, and finally the cones thread onto the axle. In this cutaway, you can see that the weight of the bike rests entirely on the bearings. Crazy. Anyway, the looseness that you can feel is when the bearings are not tightly held between the cones and the hub. This is bad! It can damage the hub.
So, first thing that we do is take off the cassette. To do this we use a special tool that fits into the lock ring. When turning left however, the freewheel turns too. To hold the freewheel in place (and avoid hamburger hands) you use a tool called a chain whip:
With the cassette off, we can disassemble the axle hardware. I usually line up the hardware in order so I don't forget the order.
Left to Right
I should point out that normally when I do this, I take off the NON drive side, there's far less hardware. I was cleaning everything, so all hardware came off. Once all the nuts, cones and washers were off, I could spy the (very dirty) bearings.
Needs cleaning big time
Poke all the bearings out, and into the cleaning frisbee they go!
Next, clean out the nasty-ass grease and smear in some fresh grease. I put enough grease in so that when I pop the bearings in they will stay put. You can kind of see the bearings held in place by the grease in the next shot:
Greased up like a pig
It's important to be sure the bearings are all covered in grease, this will ensure smooth operation and keep water out. Reassemble is the reverse of disassembly. At this point it's important to be sure to get the bearings in snugly to remove the play that caused this rebuild in the first place. It's also important not to tighten it too tight or the wheel won't turn!
Lastly, I took some break cleaner to my rotor, because I'd been touching it with greasy fingers, and you don't want to get grease on the brake pads. So, little squirt squirt, wipe wipe, all set.
Picture probably not necessary
That's about it! This is one of those projects that, once done a few times, is a very comfortable thing to do. Even fun I'd say!